Table 1.

Analysis of HPLC-purified tryptic peptides derived from p81, p76 and p38

Protein sequence		Identified as	Peptide position	Calc. mass	Exp. mass
p81	SGYLSSER	Ezrin, human	142–150	897.94	897.7
	LIPQR	Ezrin, human	151–155	625.77	625.6
p76	LFFLQVK	Ezrin, human	100–106	894.12	n.d.
		Moesin, human	100–106
		Radixin, human	101–107
		Merlin, human	117–123
p38	FHGTVK	GAPDH, human	055–060	687.80	687.4
	LTGMAFR	GAPDH, human	227–233	810.98a	810.5
	LEKPAKYDDIKK	GAPDH, human	248–259	1447.69	1447.7
	VVDLMAHMASKE	GAPDH, human	323–334	1362.59a	1362.3

n.d., not determined.

Using the SWISS-PROT protein sequence database p38 was identified as glyceraldehyde-3-phosphate-dehydrogenase (G3P1-HUMAN or G3P2_HUMAN), p76 as a member of the ERM-family (see text), and p81 as human ezrin (EZRI_HUMAN). For N-terminal amino acid sequencing up to ten Coomassie-blue stained protein bands were excised from Lämmli slab gels and the protein was digested in the gel matrix with trypsin (1 μg for the 81 and 76 kDa proteins and 2 μg for the 38 kDa protein) as described by Eckerskorn and Lottspeich (Eckerskorn and Lottspeich, 1989). The resulting peptides were eluted from the gel and seperated by reverse-phase HPLC using a C18 column (Vydac, 2.1×250 mm) with a Waters 600 HPLC (Millipore). As solvent system was used 0.1% trifluoroacetic acid in H₂O (aqueous phase A) and 0.085% trifluoroacetic acid in acetonitrile (organic phase B). Peptides were identified by Edman sequencing and mass spectrometry. Automated sequence analysis of the purified peptides (2/3) was performed using a type 473A protein sequencer (Applied Biosystems). Electrospray ionisation mass spectrometry of the peptides (1/3) was performed using a Finnigan TSQ MAT 700 mass spectrometer.

^a Met oxidized.